Add function to parse and calculate crop parameters

A new function 'parse_crop_params' has been added to parse the crop parameters. This function uses regex to parse the crop string and returns a tuple if it matches the pattern. The 'detect_crop_parameters' function is now also improved to calculate and return composite crop parameters. It now gathers all crop parameters, finds the maximum dimensions, and the minimum offsets, and composites the largest frame. If no crop parameters are found, it returns an empty string.

bd_to_avp/modules/video.py

@@ -1,4 +1,5 @@
 import atexit
+import re
 from pathlib import Path
 
 import ffmpeg
@@ -141,6 +142,13 @@ def combine_to_mv_hevc(
         raise RuntimeError("Failed to combine stereo HEVC streams to MV-HEVC.")
 
 
+def parse_crop_params(crop_string: str) -> tuple[int, int, int, int] | None:
+    match = re.match(r"(\d+):(\d+):(\d+):(\d+)", crop_string)
+    if match:
+        return tuple(map(int, match.groups()))  # type: ignore
+    return None
+
+
 def detect_crop_parameters(
     video_path: Path,
     start_seconds: int = 600,
@@ -149,6 +157,7 @@ def detect_crop_parameters(
     print("Detecting crop parameters...")
     if not config.crop_black_bars:
         return ""
+
     stream = ffmpeg.input(str(video_path), ss=start_seconds)
     stream = ffmpeg.output(
         stream,
@@ -166,12 +175,29 @@ def detect_crop_parameters(
         print(e.stderr.decode("utf-8"))
         raise
 
-    crop_param_lines = []
+    crop_params: list[tuple[int, int, int, int]] = []
     for output_line in output:
         if "crop=" in output_line:
-            crop_param_lines.append(output_line.split("crop=")[1].split(" ")[0])
+            crop_param = output_line.split("crop=")[1].split(" ")[0]
+            parsed_params = parse_crop_params(crop_param)
+            if parsed_params:
+                crop_params.append(parsed_params)
+
+    if not crop_params:
+        return ""
+
+    # Find the maximum dimensions
+    max_width = max(param[0] for param in crop_params)
+    max_height = max(param[1] for param in crop_params)
+
+    # Find the minimum x and y offsets
+    min_x = min(param[2] for param in crop_params)
+    min_y = min(param[3] for param in crop_params)
+
+    # Composite the largest frame
+    composite_crop = f"{max_width}:{max_height}:{min_x}:{min_y}"
 
-    return max(crop_param_lines, key=len, default="")
+    return composite_crop
 
 
 def upscale_file(input_path: Path) -> None: